Hi Mathieu,

quoted

Hi everybody,

I was wondering if anyone had implemented hardware flow control support
in the cpm_uart driver. If not, I would appreciate pointers regarding how
to do so.

Best regards,

Laurent Pinchart

I had. PQ2 CPM is a dedicated part which handles this aspect for you via
its microcode. This also means you can't play with it the old way and
making your own HHS with a CD/DSR :). Back to seriousness, rather this
means you needn't adding modem signal handling in cpm_uart driver. So don't
define modem_something that's an ancient reliq from the times, I guess, no
CPM was put auxillary.

So how to tell CPM to cope with HHS ? Simple, you "just" have to put SCC's
Dedicated pins the right way which depends on your board type. Remember you
can't do any HHS with SMC. Refer to Dedicated Pins chapter in the
litterature [41.4.2]. Also take a look at SCC GSMR register [20.8] and to
SCC UART mode PSMR register [21-14] to maybe use protocol specificities.

Thanks.

When you'll have your kernel ready, you would do probably something like :
	stty -F $port crtscts $SPEED

I suppose I also have to add support for the CRTSCTS flag in set_termios.

As Wolfgang said HHS works for DTE-DCE only (roughly but visually you must
have plugs opposite gender on both ends), trying DTE-DTE HHS dialog is
bound to failure despite time spend on it.

I'll disable hardware flow control if I need DTE-DTE communication.

Thanks for your help.

Laurent Pinchart